The asperity of a surface of a silicon wafer for forming a semiconductor device such as an IC or LSI is a factor which prevents an improvement of current drivability of a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), as shown in, for example, Non-Patent Document 1 and, therefore, the surface is required to be as flat as possible.
On the other hand, it is reported that when a silicon wafer is heat-treated in an Ar atmosphere at 1200° C., it is possible to form an extremely flat surface on which the atomic-level step-and-terrace morphology appears (see Non-Patent Document 2).
However, the high-temperature treatment at 1200° C. makes mass production difficult.
Meanwhile, Patent Document 1 describes that a 200 mmφ wafer surface can be atomically flattened without any slip line by performing a heat treatment in a high-purity Ar gas atmosphere at 850° C.